If you are not happy with the increase in your total rent (including the service charge), most tenants can appeal to the First-tier Tribunal (Property Chamber). This is an independent body that will recommend a market rent based on the rents charged by private landlords in the area. The appeal must reach the First-tier Tribunal before the rent increase is due.
The Tribunal cannot decide whether the rent (excluding service charge) is correctly increased under the Rent Standard.